Volume 10 (1998)

Table of Contents

No. Article


1. Kajian Sifat Asfalt-Lateks (A Study of Asphalt-Latex Properties)
Riza Atiq bin O.K. Rahmat, Arniruddin Ismail & Yeong Tuck WaiAbstract
In a hot climate, asphalt pavement will age harden faster and require substantial maintenance. Age hardening causes asphalt to be stiff and brittle. The pavement layer then becomes too hard and lose its flexibility. As a result the pavement will crack and break up. In this study natural latex is added to asphalt in order to retard age hardening. The following tests were carried out on the latex-modified asphalt: penetration, softening point, absolute viscosity and kinematic viscosity. Latexmodified asphalt with latex content of 3% and 6% by weight of mix produce different properties to justify their uses in different conditions. Six percent latex content was found to be the optimum content in retarding ageing process of asphalt as well as improving its stability. However the asphalt becomes less workable. Asphalt with three percent latex content is found to be good in workability and at the same time retain the ageing process as well as improving the stability of the asphalt.

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2. Penjanaan Perjalanan oleh Kawasan Industri (Trip Generation by Industry Area)
Riza Atiq bin O.K. Rahmat, Moh. Sofian Asmirza & Amiruddin IsmailAbstract
Presently, transport planners use the four-step transport model to forecast future transport demand and scenarios. The first and the most important step in the model is trip generation. Previous transport studies that were carried out in Malaysia did not give enough emphasis on industrial trips. In this particular study the character of each type of industry and its relationship with trip generation were examined. Regression and category analysis procedures were adopted to analyse the trip-making characteristic in order to produce suitable models. Klang Valley area was chosen for this study. A set of statistically sound model for container-trailer trips has been developed for industrial premises which cover a land area of greater than one hectare. In the case of smaller premises, a set of statistically good model for lorries, vans dan factory buses has also been developed.

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Page 11-26

3. Effects of the EDF Length and Oscillation Reflectivity on the Output Power of a 1.55 pm Ring Fiber Laser System
Mohamad K. Abdullah, P. Poopalan, Mohd A. Mahdi, Hanafi M. Said, Mohd F. Assilam & Harith B. AhmadAbstract
The effects of varying the Erbium doped fiber (EDF) length and the loop-back reflectivity of an all fiber ring laser system are presented. Two characteristics of the output power, namely the lasing threshold and the maximum power are analyzed. The reflectivity is taken as the percentage of the lasing signal that is fed (or reflected) back into the loop. The maximum output power refers to the power obtained at maximum pump power available, 115 mW. This therefore does not represent the actual maximum output power obtainable with the EDFL system which should be higher. For a particular system, there is an optimum length of EDF that gives the lowest lasing threshold. Smaller reflectivity is found to give a higher maximum output power but at the expense of a higher lasing threshold.

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Page 27-32

4. Behaviour of Trinitrotoluene in Electrokinetic Soil Processing
M. Raihan Taha, Yalcin B. Acar, Robert J. Gale & Mark E. ZappiAbstract
The behaviour and removal of trinitrotoluene (TNT) in contaminated soil under electrokinetic processes was investigated. The soil used in this study was obtained from the Hastings East Industrial Park site in Nebraska, USA. A current density of 123.3 μA/cm2 was applied to soil specimens compacted in glass cells. Test with water and a surfactant solution, SDS, as anolytes indicated that TNT concentrations in the soil sample decreased significantly at the sections closest to the cathode. This, however, was not due to removal of TNT away from the cathode. Extensive analysis indicated that the disappearance of TNT was possibly due to the transformation of TNT to TNT anions possibly due to reaction of TNT with base and reductive environment generated during electrolysis. These anions were not detected in initial analysis with high performance liquid chromatography using EPA method. The electrokinetic processes needs further engineering in order to enhance removal of TNT from soils.

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Page 33-49

5. A Plasticity Theory and Finite Element Implementation of Friction Model
Ahmad Kamal Ariffin Mohd IhsanAbstract
A friction model based on plasticity theory is presented. An interface element was used in the finite element implementation. An incremental-iterative solution strategy was suggested to simulate the non-linear problem in friction. The model was tested to simulate the friction force of the ejection of a powder compact component from a die. The numerical simaulation results were validated and shows good agreement.

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Page 51-62

6. Penentukuran Model Graviti untuk Corak Perjalanan Kenderaan Perdagangan di Lembah Klang (Calibration of Gravity Model for Commercial Vehicles Trip Pattern in Klang Valley)
Riza Atiq Abdullah O.K. Rahmat, Mohd Sofian Asmirza & Amiruddin IsmailAbstract
This study involves the analysis of commercial vehicles trip patterns in Klang Valley using the Gravity Model which are singly and doubly constrained. For every type of the Gravity Model, distance and travel time were adopted as the spatial separation between the transport zones. The models were calibrated using observed origindestination trip matrices of commerciul vans, lorries, trailer-lorries and trailercontainer- lorries. This study demonstrated that doubly-constrained Gravity Model synthesised the trip patterns more accurately forr both types of the spatial separation. Trailer-lorries and container-lorries trip patterns are synthesised more accurately using the travel time as the separation function. Unlike for other types of vehicles, travel distance as the separation function in the Gravity Model synthesised more accurately the trip patterns. In term of separation function, both the single and doubly-constrained Gravity Models using power function were found to be better than the exponential function for the three groups of vehicle i.e. heavy lorries, trailerlorries and container-lorries. However the exponential function is better in replicating the trip patterns of commercial vans and small lorries as this type of vehicles are usually used for short distance hauling.
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Page 63-81
7. Experimental Investigation on Fluidized Bed Jet Grinding
Siti Masrinda Tasirin  & Derek GeldartAbstract
Fluidized bed jet grinding is a well accepted method for producing powders with an average particle size of less than 10 μm quickly and effectively. Its use has increased steadily for grinding chemicals, minerals, pigments, pharmaceuticals, abrasives, plastics and food. Nevertheless, even though the uses are increasing, the basic mechanism of comminution within such mill is not well understood and their design and prediction of performance is therefore largely very empirical. Using coarse cracking catalyst and 2 mm i.d. jet nozzles, the effects of gas mass flowrate, separation distances and geometry of the set up on the initial grinding rate have been investigated. It was found that grinding was a consequence both of interparticle collisions in the jet region, and when a target plate was used, of abrasion on the single plate. For a given power input, target plate jet grinding gave a higher production rate and finer size of product than with two opposing nozzles.
    download buttonPage 83-97
8. Kesan Penggunaan Bahan Tambah Galian dan Nisbah Air-Simen ke atas Sifat Fizikal Konkrit Prestasi Tinggi (Effect of Mineral Admixture and Water-Cement Ratio on the Physical Properties of High Performance Concrete)
Muhammad Fauzi b. Hj Mohd Zain & Lim Chin ChiatAbstract
This paper discusses the effect of mineral admixture and water/cement ratio on the physical properties of high performance concrete. Since mineral admixtures such as silica fume, fly ash fume and ground granulated blast furnace slag are known to improve the properties of fresh concrete and increase strength and durability of hardened concrete, they are now widely used as a cement replacement materials. In this study, silica fume and fly ash fume together with chemical admixture have been used to investigate the role of mineral admixtures and water/cement ratio on the strength and durability of high performance concrete. The result shows that the effects of mineral admixtures on strength and durability of hardened concrete depends on the percentage of water/cement ratio. The study also focuses on the important role of the hydration process that produces hardened concrete of higher strength and durability.
 download buttonPage 99-111